A deck consisting of a flat steel plate stiffened with closely spaced longitudinal ribs and wearing surface on top belongs to which deck family?

• A. Steel decks
• B. Grid decks
• C. Orthotropic decks
• D. Concrete decks

Answer: (C)

This arrangement is an orthotropic deck. The flat steel plate is stiffened by many closely spaced longitudinal ribs, and a wearing surface sits on top to carry traffic. The combination creates different stiffness in the longitudinal direction (along the ribs) versus across the deck width, so the deck behaves differently in different directions—this directional or anisotropic stiffness is the defining feature of an orthotropic deck. The concrete wearing surface works in composite with the steel plate to carry loads efficiently, which is typical for orthotropic steel decks. Other options describe different concepts: a plain steel deck lacks pronounced directional stiffening, a grid deck uses a lattice of many ribs forming a grid, and a concrete deck is a solid concrete slab without the steel plate stiffeners.